var s = ["a","b","c"]
var s:[String] = [String]()

s.append("e")
s.first!
s.last!
s[0]
s.count
s[0...3] = ["a","b","c"]
s.isEmpty
s.insert("a",atIndex:0)
s.removeAtIndex(0)
s.removeLast()
s.removeAll(keepCapacity:false)
s.map({
    (str:String) -> String in 
    return str + "0"
})

